Answer
{1,3,4,6}
Work Step by Step
Find (A ∩ B) U C
We start by doing what is in the parenthesis: A ∩ B.
A ∩ B means the intersection of the elements in sets A and B.
A={1,3,4,5,9}
B={2,4,6,7,8}
To find the intersection we compare the elements of the two sets. For example I could start by looking at the elements of set A and checking to see if they are also in B. Comparing the elements of set A and set B, the only number that is in both sets is 4. So A∩B={4}.
Next we need to find {4} U C
Or {4} U {1,3,4,6}
To find the union we list all of the elements of both sets, and delete any duplicates.
4 and 1,3,4,6
Because 4 is in both sets, it only needs to be listed once. The union, then, is {1,3,4,6}
